3a,6,6,9a-Tetramethyldodecahydronaphtho[2,1-b]furan (hereinafter, indicated as “compound A”) is a fragrance component that is contained in ambergris, a pathological secretion produced in the body of sperm whale, and is an important compound indispensable as an amber-based fragrance. Compound A is produced by a chemical synthesis method using sclareol, which is extracted mainly from clary sage (Salvia sclarea L.), as a starting material. As an intermediate of compound A, 3a,6,6,9a-tetramethyldecahydronaphtho[2,1-b]furan-2(1H)-one (hereinafter, indicated as “sclareolide”) and 1-(2-hydroxyethyl)-2,5,5,8a-tetramethyldecahydronaphthalene-2-ol (hereinafter, indicated as “diol”) are known.
However, the chemical synthesis method described above has a problem that the environmental burden is heavy, and the yield or the purity cannot be obtained at sufficient level.
Meanwhile, there have been reported methods for producing the compound A by obtaining an intermediate of the compound A from sclareol by microbial conversion and cyclizing the intermediate (for example, Patent Documents 1 and 2).
Specifically, in the Patent Documents 1 and 2, separation and purification of the diol obtained by microbial conversion are carried out by subjecting a culture fluid to solvent extraction using ethyl acetate, subsequently drying the extract, dissolving the resultant extract in warm hexane/ethyl acetate or hexane/chloroform, and crystallizing the diol from the solution.
However, since unreacted sclareol or sclareolide, microorganisms, culture medium components, and the like are mixedly present in a culture fluid obtained by microbial conversion of sclareol, separation and purification of the diol only is very difficult to achieve by the solvent extraction method using ethyl acetate.
As such, there has been reported a method of filtering a culture fluid using a filter having a mesh size of a specific range to separate the bacterial cells, subsequently dissolving the residues on the filter with ethanol, filtering the solution again, and the like to recover the diol with high purity (Patent Document 3).